Process for manufacturing a semiconductor device having MIS-type field effect transistors with impurity region below the gate electrode
AssigneeHitachi, Ltd.
InventorsKazuhiro Komori, Kenichi Kuroda, Kousuke Okuyama
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Abstract
Disclosed herein is a MOS-type field-effect transistor in which a semiconductor region having the same type of conductivity as the substrate and an impurity concentration higher than that of the substrate is formed under the channel so as to come at both ends thereof into contact with the source and drain regions. The semiconductor region restricts the extension of depletion layer from the source and drain regions, and restricts the short-channel effect. The junction capacity is small between the semiconductor region and the source and drain regions.
Claims23
A process for producing a semiconductor device having a MIS-type field-effect transistor formed in a first semiconductor region of a first type of conductivity in a semiconductor substrate, comprising the steps of:
- forming a second semiconductor region in said first semiconductor region, said second semiconductor region being separated from the surface of said semiconductor substrate, and said second semiconductor region further having the same type of conductivity as said first semiconductor region and an impurity concentration higher than that of said first semiconductor region;
- forming a gate electrode on a gate insulating film on said semiconductor substrate, after said second semiconductor region has been formed;
- introducing impurities of a second type of conductivity into said first semiconductor region using at least said gate electrode as a mask, so as to provide a first introduction step, said first introduction step being effected by the implantation of ions, so that the impurity concentration of the first type of conductivity is substantially lowered in said second semiconductor region except a portion at least under said gate electrode;
- and
- introducing impurities of the second type of conductivity into said first semiconductor region using at least said gate electrode as a mask, so as to provide a second introduction step, said second introduction step forming at least a part of the source and drain regions.
A process for producing a semiconductor device having a MIS-type field-effect transistor formed in a first semiconductor region of a first type of conductivity in a semiconductor substrate, comprising the steps of:
- forming a gate electrode on a gate insulating film on said semiconductor substrate;
- forming a second semiconductor region by implanting ions in said first semiconductor region after said gate electrode has been formed, said second semiconductor region being shallower under said gate electrode than other portions, and said second semiconductor region further having the same type of conductivity as said first semiconductor region and an impurity concentration higher than that of said first semiconductor region;
- implanting impurity ions of a second type of conductivity into said first semiconductor region, so as to provide a first introduction step, so that the impurity concentration of the first type of conductivity is substantially lowered in said second semiconductor region except a portion at least under said gate electrode;
- and
- introducing impurities of the second type of conductivity into said first semiconductor region using at least said gate electrode as a mask, so as to provide a second introduction step, to form at least a part of the source and drain regions.
Dependencies are inferred from the claim text.